On Thu, Aug 23, 2012 at 04:44:27PM +0400, Cyrill Gorcunov wrote: > On Thu, Aug 23, 2012 at 08:23:18AM -0400, J. Bruce Fields wrote: > > On Thu, Aug 23, 2012 at 02:43:23PM +0400, Cyrill Gorcunov wrote: > > > Hi guys, > > > > > > here is updated version of the fdinfo via procfs series, > > > the changes from previous one are the following > > > > > > - fhandle is carried inside inotify mark but this feature > > > is CONFIG dependent to not bloat the kernel for users > > > who don't need it > > > > As Al points out, this doesn't help much: if this feature is something a > > distro will want to provide, then in practice all their users are > > eventually going to end up with it turned on. > > > > Yes, I remember what Al has said, the problem is that this data attached > to inotify mark is not just a couple of bytes but rather about 136 bytes > per mark, and encoding this fhandle will take some cycles on mark creation > as well. Thus when in a sake of c/r we simply have no other way and are > to pay some trade off cost for c/r functionality, i don't think the > regular users (and note that CONFIG_CHECKPOINT_RESTORE is off by default) > should pay same cost for nothing. That's why I made it config dependant. > Again if you still think that making it config-option is a bad idea I'll > rip this symbols off, it's not a problem. I don't have any opinion on whether there should be a configuration option. Just want to make sure the cost when it's turned on is still taken seriously. --b. > > > Could you quantify the cost somehow? > > > > About 136 bytes per inotify mark. > > > I wonder if you could get away with something less than MAX_HANDLE_SIZE? > > 128 bytes is the maximum allowable by NFSv4. In practice I don't think > > any of our filesystems need more than 40 or so right now. > > Look, Bruce, I would like to follow the limits we have #define'd in kernel, > because it makes code easier to support. I can #define some limit for > inotify fhandle but what should I print in fdinfo if say there is no > space left in buffer? > > Cyrill -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
